1. Field of the Invention
The present invention relates to a video display apparatus that is capable of viewing videos by a plurality of persons using a plurality of shutter eyeglasses, and a method for controlling the same.
2. Description of the Related Art
Conventionally, a 3D (Three Dimensional) video viewing system using a shutter eyeglass has generally been employed. Japanese Patent Laid-Open No. 08-043766 discloses a stereoscopic video system, a composite video depiction system, and the like that can cause viewers to recognize only a specific screen from three-dimensional videos or a plurality of screens.
Also, Japanese Patent Laid-Open No. 10-240212 discloses a system in which a plurality of different video content items can be synchronously viewed by a plurality of persons using a plurality of shutter eyeglasses. In this system, N video signals are periodically displayed on the same screen by time-division. When a user selects any one of the N video signals displayed on the screen, the plurality of shutter eyeglasses open and close in response to the period of the selected video signal.
In the conventional technique, responding to changes in the number of viewable video content items at the same time by a plurality of persons is difficult. In the technique disclosed in Japanese Patent Laid-Open No. 10-240212, the frame rate (refresh rate) for the display device is not changed even when the number of video content items to be viewed is changed. More specifically, even when four persons view the same video content, the inputs from the four input terminals are still in effect, and their subsequent processing sections also always need to be operated continuously, whereby the load of the entire system is not reduced. In order to optimize the load of the entire system, it is contemplated that the frame rate (refresh rate) of the display device can be switched when the number of video content items to be viewed has been changed. However, when the discontinuous frame of the synchronization signal occurs during switching, the video image is likely to break up. More specifically, since the timing of the synchronization signal also changes in association with the frame rate (refresh rate), the operation of the display device side immediately after a change in frame rate becomes unstable, resulting in the breaking up of the video image or drop-out of video images.
Accordingly, the present invention provides a video display apparatus in which the viewers can ensure that there is no viewing of video images that have broken up when the frame rates of the video content items are changed in association with the change in the number of video content items which are to be viewed.